Poster Presentation ANZOS-Breakthrough Discoveries Joint Annual Scientific Meeting 2018

Comparing Two Exercise Training Doses on Cardiac Autonomic Function in Adults with Overweight/Obesity and Type 2 Diabetes: A Randomised Controlled Trial (#308)

Emily R Cox 1 , Shelley E Keating 1 , Trishan Gajanand 1 , Jeff S Coombes 1
  1. School of Human Movement and Nutrition Sciences, University of Queensland, St Lucia, QLD, Australia

Introduction: Compromised cardiac autonomic function (CAF) is an independent predictor of cardiovascular disease and all-cause mortality in adults with T2D. High-intensity interval training (HIIT) has been shown to improve CAF, but it’s unclear whether a lower volume of training produces equivalent effects. We aimed to compare the effects of low-volume combined aerobic and resistance HIIT (C-HIIT) with combined aerobic and resistance moderate intensity continuous training (C-MICT) on CAF in adults with overweight/obesity and T2D following 8-weeks of supervised training and 10-months of home-based training.

Methods: 35 individuals (age 59.5±8.7y, BMI 34.0±7.7kg/m2, 63% male) diagnosed with T2D (mean HbA1c 7.6±1.1%) were randomly allocated to 8-weeks of either supervised C-HIIT (1x4min high-intensity aerobic @ 85-95% HRpeak plus resistance training, 3 times/week), supervised C-MICT (52.5min @ 55-65% HRpeak, 2 times/week; 22.5min @ 55-65% HRpeak plus resistance training, 2 times/week) or control (usual care). Participants then completed 10-months of home-based training (same protocol), with once monthly supervised sessions. CAF was quantified using heart rate variability (HRV), and heart rate recovery (HRR) following a maximal exercise stress test (EST).

Results: There were no significant differences in any CAF variables between C-HIIT and C-MICT at either time point. Both C-HIIT and C-MICT significantly increased absolute change in HR at 2minutes post-EST (36±6.0bpm to 43.1±6.8bpm, p=.012; 38±10.4bpm to 43±9.3bpm, p=.039 respectively) compared to control after 8 weeks. There was a significant effect of time for mean RR interval length (p=.004) and mean HR (p=.004) after 12-months, but no significant differences between groups.

Conclusion: Exercise training improved CAF in adults with T2D following 8-weeks of supervised training and 10-months of home-based training. There were no differences in improvements between C-HIIT and C-MICT, despite C-HIIT requiring one third of the time commitment. Therefore, C-HIIT is a time efficient alternative to C-MICT to improve CAF in T2D.